If the IIS Lockdown Tool has been used, you may want to try reverting the changes made by the utility. This can be accomplished by running the IIS Lockdown Tool again and allowing it to revert the previously made changes. Once this process is complete, a restart of the IIS and SEPM services should be performed. A full system restart may or may not be required.
For more information on the IIS Lockdown Tool, its uses and what changes it makes, please see Microsoft's website at the following URL.
Note: The IIS Lockdown Tool is designed only for IIS 4.0 (Windows NT 4.0), 5.0 (Windows 2000) and 5.1 (Windows XP). Its use is not supported on other versions of IIS and the results of doing so are unknown.